Scientists hunting unseen dark matter are looking deeper into the shadows. With searches for a favored dark matter candidate—weakly interacting massive particles (WIMPs)—coming up empty, physicists are now turning to the hypothetical "dark sector": an entire shadow realm of hidden particles. The concept "has been percolating for 7 or 8 years, but it's really coming to the fore now," says Jonathan Feng, a theorist at the University of California, Irvine (UCI).

This week, physicists will meet at the University of Maryland, College Park, for a workshop, sponsored by the U.S. Department of Energy (DOE), to mull ideas for a possible $10 million dark matter experiment that could go ahead in the next few years. The effort would complement the agency's current experiments, including the flagship WIMP search, LZ, a $76 million subterranean detector under construction in Lead, South Dakota. And many researchers believe DOE should focus on the dark sector. Jim Siegrist, DOE's associate director for high-energy physics in Washington, D.C., says the goal is to fill in any gap in DOE's searches for dark matter, which makes up 85% of the universe's matter: "Is there anything we're missing?"

WIMPs, dreamed up in the 1980s, once seemed the perfect candidate for dark matter, which shapes the visible universe with its gravity. WIMPs would weigh a few hundred times as much as a proton and interact only through gravity and the weak nuclear force. A simple calculation suggests just enough of them should linger from the big bang to account for dark matter today—a selling point known as the "WIMP miracle." In addition, WIMPs emerge naturally in many versions of supersymmetry, a concept that solves key technical problems in the standard model of the known particles. However, physicists have yet to detect WIMPs bumping into atomic nuclei in underground detectors. And the world's most powerful atom smasher, the Large Hadron Collider (LHC) in Switzerland, has seen no sign of supersymmetry or WIMPs.

The no-shows have led physicists to turn to the dark sector. They speculate that dark matter might consist not of a single massive particle tacked onto the standard model, but of a slew of lighter particles and forces with tenuous connections to known particles (see illustration). For example, in the familiar universe, massless photons convey the electromagnetic force; in the dark sector, a massive dark photon would convey a dark version of electromagnetism. Theorists generally expect that ordinary and dark photons would subtly intertwine or "mix." Very rarely, then, a particle interaction that would normally produce a high-energy photon would instead produce a dark photon.

Scientists hunting unseen dark matter are looking deeper into the shadows. With searches for a favored dark matter candidate—weakly interacting massive particles (WIMPs)—coming up empty, physicists are now turning to the hypothetical "dark sector": an entire shadow realm of hidden particles. The concept "has been percolating for 7 or 8 years, but it's really coming to the fore now," says Jonathan Feng, a theorist at the University of California, Irvine (UCI).

This week, physicists will meet at the University of Maryland, College Park, for a workshop, sponsored by the U.S. Department of Energy (DOE), to mull ideas for a possible $10 million dark matter experiment that could go ahead in the next few years. The effort would complement the agency's current experiments, including the flagship WIMP search, LZ, a $76 million subterranean detector under construction in Lead, South Dakota. And many researchers believe DOE should focus on the dark sector. Jim Siegrist, DOE's associate director for high-energy physics in Washington, D.C., says the goal is to fill in any gap in DOE's searches for dark matter, which makes up 85% of the universe's matter: "Is there anything we're missing?"

WIMPs, dreamed up in the 1980s, once seemed the perfect candidate for dark matter, which shapes the visible universe with its gravity. WIMPs would weigh a few hundred times as much as a proton and interact only through gravity and the weak nuclear force. A simple calculation suggests just enough of them should linger from the big bang to account for dark matter today—a selling point known as the "WIMP miracle." In addition, WIMPs emerge naturally in many versions of supersymmetry, a concept that solves key technical problems in the standard model of the known particles. However, physicists have yet to detect WIMPs bumping into atomic nuclei in underground detectors. And the world's most powerful atom smasher, the Large Hadron Collider (LHC) in Switzerland, has seen no sign of supersymmetry or WIMPs.

The no-shows have led physicists to turn to the dark sector. They speculate that dark matter might consist not of a single massive particle tacked onto the standard model, but of a slew of lighter particles and forces with tenuous connections to known particles (see illustration). For example, in the familiar universe, massless photons convey the electromagnetic force; in the dark sector, a massive dark photon would convey a dark version of electromagnetism. Theorists generally expect that ordinary and dark photons would subtly intertwine or "mix." Very rarely, then, a particle interaction that would normally produce a high-energy photon would instead produce a dark photon.

This is where “dark energy” comes in. According to the Lambda Cold Dark Matter (Lambda-CDM) model, which is the framework that governs our current understanding of the origin and evolution of the universe, dark energy and dark matter make up nearly 95 percent of the cosmos. Dark energy, which is an as-of-yet undetected force that comprises 68 percent of the universe, is believed to be responsible for its accelerated expansion.

I was under the impression, Q-reeus, that both DE and DM are currently only hypothesized.
Ergo, it would seem that neither Dark Energy, nor Dark Matter have yet been shown to be actually manifest in nature/reality, much less completely understood or explained.

IMO, There are other options/models one should consider when conceptualizing the universe, its structure, and its evolution. But the 'peer' community here won't allow such without demanding, under threat of forum banning, that such ideas must comply with the Standard Model. In time, the truth will out! HSIRI

IMO, There are other options/models one should consider when conceptualizing the universe, its structure, and its evolution. But the 'peer' community here won't allow such without demanding, under threat of forum banning, that such ideas must comply with the Standard Model. In time, the truth will out! HSIRI

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No, if you have any, then shoot it. None will ban you for putting alternative ideas.

My question is the idea of dark mater is a fudge factor in order to give the desired answer for a proposed theory ?

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Replace "fudge factor" with the words "placeholder" and that would seem fair.
The current theory says there must be "matter" there even though we do not see it or can detect it other than by its apparent gravitational effects.
If our current ideas on gravity are correct the suggestion is dark matter must exist if our current ideas are wrong the need for dark matter may disappear.
But at this time our sums demand it even though we can not yet get the full picture.
By investigating sooner or later we will understand more. We may need to change our current theories so they dont yield dark matter we may not but so far it looks as if dark matter is real.
If you think it is nonsence all you need do is provide a better theory to explain our observations which currently tell us there is present this stuff we can only call dark matter.
Alex

I was under the impression, Q-reeus, that both DE and DM are currently only hypothesized.
Ergo, it would seem that neither Dark Energy, nor Dark Matter have yet been shown to be actually manifest in nature/reality, much less completely understood or explained.

Click to expand...

Maybe I have been too caught up in following mainstream categorization. So sure as per examples, theorists can come up with variously sophisticated and elaborate models that have some kind of dual nature dark fluid that shifts character chameleon style from epoch to epoch. And splits character within a given epoch. Whatever the truth to any of it, #4 was thrown in with no attempt by timojin to link it to the thread topic. Therefore it rightly deserved to be aired in a separate thread.

We went over that kind of thinking (universe as a ball expanding into a preexisting void) in another thread. I see you have continued difficulty accepting modern cosmological perspective. Not to worry, luckily none of our beliefs re cosmology effects the running of the local sewerage works. Just as well.

Michael, as an explanation of my post #10: IMO (I repeat . . . IMO), prior to our now-observable universe, there existed an extremely-high, pure energy condition (E(1)). Some portion of E(1) - by a viable (quantum?) mechanism - began converting to mass (assume 'rest mass' for simplification via m=E/c x c, via virtual particle pair production with nonequilibrium pair anihilation) and the process continues. The current observable universe contains some remaining 'pure' energy (E(2)), plus all of the mass that we currrently observe/measure. That combination likely yielded a condition with a net depleted spatial attribute (overall, appears to observers to be a decreased volume component). This 'energy conversion' process proceeds outward (from an original BB, or other), so that the outer 'edge' (aka: energy conversion reaction front?) of the visible (observable) universe appears to be receding (net observation: expansion of visible portion of the universe). Mods feel free to move to Alternate Theories or Cesspool as you may warrant!

Nit-pickers please note: this foregoing IDEA is IMO, Not a claim, Not a proven fact , Not a theory, perhaps Not even a hypothesis! And I offer nothing in the way of scientific evidence - its an IDEA!

Replace "fudge factor" with the words "placeholder" and that would seem fair.
The current theory says there must be "matter" there even though we do not see it or can detect it other than by its apparent gravitational effects.
If our current ideas on gravity are correct the suggestion is dark matter must exist if our current ideas are wrong the need for dark matter may disappear.
But at this time our sums demand it even though we can not yet get the full picture.
By investigating sooner or later we will understand more. We may need to change our current theories so they dont yield dark matter we may not but so far it looks as if dark matter is real.
If you think it is nonsence all you need do is provide a better theory to explain our observations which currently tell us there is present this stuff we can only call dark matter.
Alex

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I don't have any theory to replace , but it seems a little funny 85 % of our matter we can nor test it, It seems to me the initial premises could be questioned. This dangling Dark matter is a subject over 50 years . I remember they tried to bring the temperature to near O c 85 % of the matter been dark we should be swimming in it.

I don't have any theory to replace , but it seems a little funny 85 % of our matter we can nor test it, It seems to me the initial premises could be questioned. This dangling Dark matter is a subject over 50 years . I remember they tried to bring the temperature to near O c 85 % of the matter been dark we should be swimming in it.

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On a personal level I agree.
I liked what Vera Ruban said about dark matter, which I found in an old astronomy magazine.. In effect she said she would rather that the theories be altered rather than inventing a new particle.
For me I think the need for dark matter says we are very wrong about something and I would be working from the change the theory end rather than entertain most of the matter in the universe we can not see.
I think gravity works like a pressure system and I bet you would not need dark matter and dark energy would not be mysterious however science does not derive from my good or bad ideas and I really believe we can only move forward with what our tested tested theories tell us we can expect. That way we will reach a point where dark matter or its absence will be better understood.
Working on the matter must lead us somewhere.
Alex